Film-Tech Forum ARCHIVE: National Searchlight carbons origin?

This is topic National Searchlight carbons origin? in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

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Posted by Warren Smyth (Member # 1838) on 10-05-2003, 10:05 PM:

I have been using a supply of 7mm X 14inch positive carbons with success for projection. They are part of a lot of old stock I bought some time ago. Judging by the early corrugated cardboard boxes, they could be from as far back as the 1940s. They were made by National but the carbons have 'SEARCHLIGHT' written on them at the end. I'm wondering if any older timers remember seeing these and whether they were actually made for searchlight use, or if this was just a name for their type. They are high intensity carbons and burn just the same as any other I've used. Any carbons I've seen used for searchlights have been much thicker and not copper coated resembling low intensity type. Can anyone throw some 'light' on the subject?

Posted by William H. Ward (Member # 1797) on 10-06-2003, 03:18 PM:

Hey Warren.... I've seen some modified projection arc-lamps aboard some ships (older) mounted alongside the bridge on both sides. These lamps were Brenkert Enarc with the front casting modified with a larger opening (18-24 inches). Assumption is they burned either the 6 x 7mm or 7 x 8mm trim. The carbons made for them were probably marked SEARCHLIGHT. The arc color temperture was the same as regular projection arcs (5500 deg K.)The only other carbons I've seen for searchlight use is a 10mm x 18"black positive used on Navy search & rescue aircraft in the late 50's, and on some 36" searchlights on navy ships. Also the large 72" searchlight you still see today. That burns the 5/8" positive with a 1/2" neg at 190amps and/or the 16mm x 28" positive carbon with a 9/16" negative at 225amps. All those carbon trims were marked "NATIONAL" "SEARCHLIGHT". These carbons are very expensive to buy. Of course, most high intensity light sources today are all xenon. Not as DRAMATIC as a carbon arc..

Posted by Warren Smyth (Member # 1838) on 10-06-2003, 04:15 PM:

Thank you William. The fact that you say the larger carbons were marked 'Searchlight' suggests that mine were also made for this purpose. It's most unlikely that National would have been inconsistent with their markings.

As you say, they are the same colour temperature as projection carbons and burn just as well. The only difference is that the copper coating may be very slightly thinner. This could be the result of the period in which they were made however, rather like 'Victory' carbons during the war. I'm under running them at 40 amps and they are fine.